On the way to the target of a renewable full supply in the range of power generation until mid-century, fossil fuels will still be of importance and must cover in the medium term most of the energy needs. Against this background, it is still questionable how the bridge to this target will look like and what form of the conventional energy supply is suitable to accompany best the development of the renewable energies.

This analysis has its focus on the question which particular role the use of natural gas might play in this context and if it can fulfill a bridging function: In contrast to coal, natural gas is a considerably low-carbon and low-emission fuel and contrary to nuclear power a low-risk technology. The use of natural gas also offers in technological respect many advantages. Moreover, well developed gas pipeline networks and -storages are already available for this performance-bound energy form, which can also be of future use for the system integration of renewable energies by newly developed methods (Power to Gas).

However, this is only profitable if natural gas serves as fossil and therefore as finite energy source. Furthermore, many different actors critically examine the political relations with important suppliers of natural gas, primarily those with Russia. Therefore, the aim of this paper is on the one hand to work out the aforementioned strengths of natural gas as possible bridging technology and on the other hand to provide facts about the present and future natural gas supply. It is to create an objective basis which neither is to cause fears or to appease these facts.

In this context, the chapters will deal will the following questions:
1. What kind of natural gas applications are typical at present and can be considered as sustainable for the future?
2. What role does natural gas play for the present and future energy supply - can natural gas take over a bridging function and make possible a complete renewable energy supply?
3. Wherefrom do we get natural gas nowadays and what is going to change in future - does the use of natural gas consequently involve higher risks for energy systems?

The key results of the brief study are the following:

• In future, considerable amounts of natural gas can be reduced on the heat market on the one hand by consequent energetic modernising insulation of buildings and on the other hand by using highly efficient gas applications.
• In the energy sector natural gas plays a central role both as far as the low-greenhouse gas and highly efficient power generation in combined-cycle and in CHP plants are concerned and also as far as the central and distributed provision of system services for integrating the renewable power sources is concerned.
• Both considering the miscellaneous and flexible natural gas applications and analysing the most significant climate protection scenarios show: Natural gas is the energy source which may fully take over a bridging function during the transition period up to the full supply with renewable energies.
• Despite its finiteness the supply with natural gas in Germany will be assured for the next centuries under appropriate political conditions. The high possible savings on the heat market, alternative supply chains (e.g. the Baltic Sea pipeline) and the supply options like LNG, biogas and perspectively hydrogen additions as well as synthetic methane obtained by renewable surplus energy also ensure the future use of natural gas without any danger for increased dependence.